1. Field of the Invention
This invention relates to ventilation systems for vehicles, and more particularly to a counterflow ventilation system for a long life vehicle such as a mail or parcel cargo distribution vehicle.
2. Description of the Related Art
Most vehicle ventilation systems arise from fans used in quarters adjacent the hot engine block or engine compartment. Consequently, such ventilation systems pull in hot air adjacent the engine compartment and transmit it to the confines of the interior of the nearby passenger compartment. While air conditioning and the like may be used to cool such air, the drawing of such air from adjacent the engine compartment leads to preheating of such air before it may be cooled by air conditioning or the like. When such air is merely vented into the interior of the passenger compartment, the heat absorbed by the air heats the passenger compartment.
While air conditioning may be used to cool such air, some vehicles do not have air conditioning or otherwise the air conditioning is disabled. This latter problem may be particularly true with U.S. mail and other residential and commercial parcel and package carriers as the air conditioning systems are sometimes disabled in such vehicles. Additionally, such vehicles by necessity may heat up due to the greenhouse effect and the locked confines of the glass-enclosed passenger compartment. In fact, such vehicles may have extensive glass panels surrounding the passenger/driver compartment in order to provide maximum visibility. Consequently, greenhouse-type heating can become a significant impediment to use.
In long life vehicles such as those used by the United States Postal Service, a cargo area is partitioned off by panels and a door from a passenger, or driver's, compartment. The cargo compartment has few windows, but does have two vents located on either side of the vehicle. The vent on the right side of the vehicle is generally above the exhaust. When the vehicle is idling or otherwise running, but not moving, exhaust fumes may be present adjacent this rear vent. On the left side of the vehicle, a similar vent is present. Generally, there is no exhaust on the left side of such a long life vehicle and the air adjacent this rear vent is relatively free from exhaust fumes.
Covers are present for both the right and left rear vents present in the upper corners of the cargo compartment of such long life vehicles. These vents may be articulated to scoop air inwards by flaring outward in a forward-facing manner. However, such positioning of the covers allows rain to enter into the vents or to be directed towards them. Under such conditions, the covers can be articulated so that they flare outward, facing rearwardly, such that the forward motion of the long life vehicle forces the rain to hit the cover, leaving the rear vents generally free from the surrounding precipitation.
The passenger compartments of such long life vehicles are enclosed on three sides by extensive glass panels. Sliding doors on left and right sides have upper glass partitions which may slide down into the lower portion of the doors. These doors and their windows must be closed and locked completely when the mail carrier temporarily leaves the vehicle in order to deliver mail. The locked condition of the long life vehicle protects the undelivered mail held in the cargo compartment. The front windshield of the long life vehicle is transparent and spans the width of the vehicle. The driver's seat for such a long life vehicle is on the right hand side, generally opposite the left hand side driver's seat present in American automobiles.
It is to be expected when the long life vehicle is left in a closed and locked condition while the mail carrier is executing mail delivery duties or the like, that the sun shines in through the glass windows of the vehicle and, by the greenhouse effect, serves to heat up the confines of the long life vehicle. In some areas of the southwest, the interior temperature of such long life vehicles can rise as high as 170.degree. F. Such high temperatures apply thermal stress not only to the contents of the long life vehicle while it is closed, but also upon the driver and any other occupants of the vehicle while it is in motion.
Using the ventilating blower or auxiliary fan originally included with many such long life vehicles only serves to circulate hot air that has been preheated by the proximity (in the case of the blower) to the hot engine compartment and by hot conditions created in the closed and locked van. However, upon traveling a short distance, the cargo compartment of the long life vehicle has a tendency to cool down rather quickly due to the presence of the vents. The forced air flow arising when the covers face forwardly serve to inject air into the cargo compartment.
It would therefore be a significant improvement in the art to provide the fresh air available to the cargo compartment to the driver's compartment where the individuals executing their duties could be subject to less heat and thermal stress.